CWE-681: Incorrect Conversion between Numeric Types

Code Examples & CVEs

Demonstrative Examples

In the following Java example, a float literal is cast to an integer, thus causing a loss of precision.

BadJava

int i = (int) 33457.8f;

This code adds a float and an integer together, casting the result to an integer.

Normally, PHP will preserve the precision of this operation, making $result = 4.8345. After the cast to int, it is reasonable to expect PHP to follow rounding convention and set $result = 5. However, the explicit cast to int always rounds DOWN, so the final value of $result is 4. This behavior may have unintended consequences.

BadPHP

$floatVal = 1.8345;$intVal = 3;$result = (int)$floatVal + $intVal;

In this example the variable amount can hold a negative value when it is returned. Because the function is declared to return an unsigned int, amount will be implicitly converted to unsigned.

If the error condition in the code above is met, then the return value of readdata() will be 4,294,967,295 on a system that uses 32-bit integers.

BadC

unsigned int readdata () {int amount = 0;...if (result == ERROR)amount = -1;...return amount;}

In this example, depending on the return value of accecssmainframe(), the variable amount can hold a negative value when it is returned. Because the function is declared to return an unsigned value, amount will be implicitly cast to an unsigned number.

If the return value of accessmainframe() is -1, then the return value of readdata() will be 4,294,967,295 on a system that uses 32-bit integers.

BadC

unsigned int readdata () {int amount = 0;...amount = accessmainframe();...return amount;}

Observed CVE Examples (6)

CVE-2022-2639

Chain: integer coercion error (CWE-192) prevents a return value from indicating an error, leading to out-of-bounds write (CWE-787)

View Details

CVE-2021-43537

Chain: in a web browser, an unsigned 64-bit integer is forcibly cast to a 32-bit integer (CWE-681) and potentially leading to an integer overflow (CWE-190). If an integer overflow occurs, this can cause heap memory corruption (CWE-122)

View Details

CVE-2007-4268

Chain: integer signedness error (CWE-195) passes signed comparison, leading to heap overflow (CWE-122)

View Details

CVE-2007-4988

Chain: signed short width value in image processor is sign extended during conversion to unsigned int, which leads to integer overflow and heap-based buffer overflow.

View Details

CVE-2009-0231

Integer truncation of length value leads to heap-based buffer overflow.

View Details

CVE-2008-3282

Size of a particular type changes for 64-bit platforms, leading to an integer truncation in document processor causes incorrect index to be generated.

View Details

Source-backed guidance

Additional facts reviewed against primary or authoritative security sources.

Verify controls for CWE-681 with SSDF evidence

Use NIST SSDF verification and vulnerability-response practices to detect CWE-681, Incorrect Conversion between Numeric Types, throughout the product lifecycle. Derive review questions, static or dynamic checks, and negative tests from the CWE's causal behavior; define the components and lifecycle stages each check covers; and retain findings with enough evidence to distinguish the root cause from symptoms and impacts. Track escapes and false negatives, then improve the verification plan after every confirmed occurrence.

NIST SP 800-218 Secure Software Development Framework — National Institute of Standards and Technology

Address Incorrect Conversion between Numeric Types during Implementation

MITRE associates mitigation with Implementation; documented detection approaches include Automated Static Analysis; recorded impacts include Unexpected State, and Quality Degradation. Use these source-defined anchors to turn CWE-681 into implementation, review, and verification checks for the affected component.

CWE-681: Incorrect Conversion between Numeric Types — MITRE CWE

Triage CWE-681 against known exploitation evidence

Use CISA's Known Exploited Vulnerabilities catalog to test whether a vulnerability mapped to CWE-681, Incorrect Conversion between Numeric Types, has evidence of exploitation in the wild. Confirm the CVE-to-CWE root-cause mapping independently before attaching the example, then capture the affected product, required action, and remediation deadline. A missing KEV match is not evidence that the weakness is unexploited, and a KEV entry must not be generalized to every occurrence of this CWE.

Known Exploited Vulnerabilities Catalog — Cybersecurity and Infrastructure Security Agency

Apply precise root-cause mapping to CWE-681

Apply MITRE's full root-cause mapping guidance when using CWE-681, Incorrect Conversion between Numeric Types. Separate weakness language from attacker prerequisites and technical impact, check the entry's abstraction and vulnerability-mapping notes, and prefer the most specific Base or Variant supported by the evidence. Record the rejected alternatives and require an independent review before the mapping is used for remediation trends or program metrics.

CVE to CWE Root Cause Mapping Guidance — MITRE CWE

Validate CWE-681 with root-cause mapping checks

Apply MITRE's root-cause mapping quick tips to CWE-681, Incorrect Conversion between Numeric Types. Confirm the finding describes the causal weakness rather than an impact or attack pattern, compare the abstraction and mapping notes with plausible alternatives, and have a second reviewer challenge the selection. Preserve the evidence and reasoning so recurring defects can be measured against one consistent identifier.

CVE to CWE Root Cause Mapping Quick Tips — MITRE CWE

Frequently Asked Questions

What is CWE-681: Incorrect Conversion between Numeric Types?+

CWE-681: Incorrect Conversion between Numeric Types is a Common Weakness Enumeration (CWE) entry maintained by MITRE. When converting from one data type to another, such as long to integer, data can be omitted or translated in a way that produces unexpected values. If the resulting values are used in a sensitive context, then dangerous behaviors may occur.

What are the security consequences of Incorrect Conversion between Numeric Types?+

If exploited, CWE-681 (Incorrect Conversion between Numeric Types) it can compromise Other and Integrity, leading to outcomes such as Unexpected State and Quality Degradation.

How do you prevent or mitigate Incorrect Conversion between Numeric Types?+

Recommended mitigations for CWE-681 include: Avoid making conversion between numeric types. Always check for the allowed ranges.

Which programming languages are affected by Incorrect Conversion between Numeric Types?+

CWE-681 commonly affects C and Not Language-Specific. Note that weaknesses are often language-agnostic patterns, so secure coding practices apply broadly.

What are real-world examples of Incorrect Conversion between Numeric Types?+

MITRE documents real CVEs mapped to CWE-681, including CVE-2022-2639, CVE-2021-43537, CVE-2007-4268, CVE-2007-4988 and CVE-2009-0231. You can look up the full details of each CVE, including CVSS scores and remediation guidance, on our CVE Lookup tool.

What is the difference between a CWE and a CVE?+

A CWE (Common Weakness Enumeration) like CWE-681 describes a category of software weakness — the underlying flaw type. A CVE (Common Vulnerabilities and Exposures) identifies a specific, real-world vulnerability in a particular product. In short, a CWE is the kind of mistake, and a CVE is an instance of that mistake being found in software.

CWE-681: Incorrect Conversion between Numeric Types

Technical Details

Applicable To

Security Consequences

Scope

Impact

Mitigation Strategies

Phase

Description

Detection Methods

Code Examples & CVEs

Demonstrative Examples

Observed CVE Examples (6)

CWE Relationships

Parent Weaknesses

Source-backed guidance

Verify controls for CWE-681 with SSDF evidence

Address Incorrect Conversion between Numeric Types during Implementation

Triage CWE-681 against known exploitation evidence

Apply precise root-cause mapping to CWE-681

Validate CWE-681 with root-cause mapping checks

Frequently Asked Questions

Learn More